Satellite station antenna system



Oct. 7, 1941. J c, McNARY AL 2,258,186

SATELLITE STATION ANTENNA SYSTEM Filed March 9, 1939 s sheets-sheet 1 Oct. 7, 1941. J. c. MQNARY ETAL SATELLITE STATION ANTENNA SYSTEM Filed March 9, 1959 3 Sheets-Sheet 2 Oct. 7, 1941. J. c. M NARY EI'AL SATELLITE SI'ATION ANTENNA SYSTEM Filed March 9, 1939 3 Sheets-Sheet 3 1 ezazive ma 56 1194956.

Patented Oct. 7, .1941

SATELLITE STATION ANTENNA SYSTEM 7 James C. McNary and Joseph A. Chambers, Mont I gomery County, Md., assignors to Electronic Developments Corporation, a corporation of 7 Maryland I '12 Claims.

Our invention relates to antenna systems for radio transmission and more particularly to an arrangement of antennas capable of effecting desirable improvements in the-operation of repeater or satellite systems for radio broadcasting.

A number of schemes have heretofore been proposed for operating satellite stations for broadcasting and other radio uses which involve a main station transmitting to one, or more satellite, repeater or'booster. stations, the latter comprising a receiving antennasystem for pick ing up signals from the main station, amplifying apparatus for increasing the level of the received signals, anda transmitting. antenna system for reradiatingthe signals. It is essential to the successful operation of'such a system that the two antennas of the repeater station be related in such manner that the receiving antenna is not responsive to signals from the repeater sending antenna while it maintains more or less normal response to signals from'the main station in orv der to avoid singing or oscillationoflthe system.

"In all previously proposed arrangements. of which we are aware it has been. necessary to separate the two satellite antennas by a consid,-

erable distance in order to. minimize the re-- sponse' of the satellite receiving antenna to the satellite sending antenna. .Such degree of separation is not always feasible or desirable, par- .ticularly where the satellite station is located in a city or elsewhere where. ground space is restricted and costly. v y

object of the invention is therefore to provide-an arrangement of satellite receivingand sending antenna systems immediately adjacent each other, so that the station occupiesa minimum of ground space, andthis is accomplished without in any way neglecting the rather strict electrical requirements essential to successful operation.

In the accompanying going and otherobjects and advantages invention are realized.

. In the drawings:

portion ofan antenna structure embodying the principles of theinvention; J Fig. 2. is atop, plan view ofthe parts shown in Fig. 1; V

Fig. 3 is acentral vertical section taken on the Fig. 4 is a horizontalsection taken on the line 4-4 of Fig. 3; i

. Fig, 5 is a side elevational View .ofa complete drawings we show certain illustrative embodiments by which the fore- Application March 9', 1939, Serial No. 260,874

antenna structure and certain appurtenant apparatus; I

Fig. 6 shows a typical vertical-plane radiation pattern of a quarter-wave vertical antenna-of I the kind commonly used in broadcasting,the figure indicating the relative field intensity at unit distance from the antenna;

Fig. '7 is a schematic representation out a dipole antenna which may be used in, place of the loop antenna shown in Figs. 1, 2, 3 and 5;

Fig. 8 is a perspective view-of such dipole antenna; and p i Fig. 9 is a fragmentary side elevational view of an antenna structure showing a modification of the embodiment of the invention illustrated in Fig. 5.

The intensity or field radiated by a vertical radiator such as is commonly used in radiobroadcasting varies with varying angles .above the earths surface. Theoretically, the field radiated toward the zenith is of zero intensity, and

the intensity at unit distance. increases from zero as the zenith angle increases, reaching a maximum whenthe zenith angle is 90", which corresponds to transmission; along the earth's surface. Fig. 6 of the appended drawing shows a plot of the theoretical, field intensity at unit distance from a quarter-wave vertical antenna of the kind commonly used by broadcasting sta-v The field intensity directly above such a tions. radiator is a minimum. In practicing our in-. vention we place the receiving antenna of the satellite station directly above the sending an- Figure 1 is a side elevational view of the upper tenna of that'station, at substantially'zero zenith 3 angle, where the field intensity of the sending. antenna is substantially zero' or at least rela' -i tively low, or we dispose portions of the receiving antenna in a zone containing the field of mini- 7 a mum intensity and on opposite sides of it.

Because the receiving antenna must bereason ably efiicient in picking up signals from the main station, it must have sizeable linear dimensions. It is evident that it would be extremely difficult in actual practice to position a receiving antenna of sizeable linear dimensions in the exact spot above the sending antenna where'the fieldof the sending antenna is of. zero intensity or of sufficiently low intensity to permit successful" operation of the entire system. However, it is possible'to arrange the receiving antenna to pick up atv least two components of signalfromlthe repeater sending antenna and balancejthem-to zero, This balancing can be efiected by p the character of connection between the receiving antenna and the restv ofthe circuit, or it can be to zero or some substantially. low' value while maintaining more or less normalresponse to the main station.

Fig. 5 illustrates one such arrangement,

this figure, I indicates a receiving loop, which is connected to a transmission line 2 by any appropriate conductor (not shown). A vertical radiator is composed of the members 7 two appear in Fig. 5 and four are visible in Fig. 4, but which of course may be provided in any convenient number. The earths surface is designated 4. An amplifying system 5 is connected by a transmission line 6 to the coupling house I, which in turn is connected by the feeder wire 8 to the shunt-fedantenna system.

The antenna I, which in the preferred embodiment of the-invention is of loop form and-is so shown in 'Figs. 1,2, 3 and 5', is mounted substantially upright, more or lessicentrally above the axis of the vertical radiator. The plane of the loop is preferably so oriented as to include the main station. While the loop may be shielded and balanced electrically with respect to the structure on which it is mounted, it is possible to use an unbalanced, unshielded loop.

Although the parts in Fig. 5 are not drawn relatively to scale, since it has been deemed expedientto exaggerate some parts at the expense of others in order to render the disclosure more clear, itwill be evident from the figure that the sides. of the loop project laterally from the axisof the vertical radiator 3, so that these sides will' have voltages induced in them from the field of the sending antenna. However, such voltages produce currents in the loop which areout of phase and which, when proper adjustment is made. cancel to zero or to some value sufficiently low to be entirely compatible withsuccessful operation of the system. The loop may be connected directly to a transmission line running to the bottom of the antenna structure, or it may energize a pre-amplifier which in turn is coupled to a transmission line.

Our experience in adjusting the loop antenna in the present repeater system demonstrates that the requisite positioning of the loop with relation to the main station and with relation to the radiator of the repeater station can best be effected by means of remotely controlled apparatus for altering the physical position of the loop. Initially the loop is placed in approximately correct position, but minor adjustments will be required to perfect the positioning, and'from time to time corrective adjustments will be found necessary. IA sort of universality of movement is desirable for the loop, in order that it may be accurately positioned at substantially any adjusted position within, of course, the limits imposed by the apparatus and the range of move-. ment permitted by it. Adjustable positioning means of satisfactory capacity may assume a variety of particular forms, as may the actuating controls and energy medium therefor. Figs. 1-

to 4'inclusiveillustrate'a practical embodiment.

"on a carriage I9 which is driven along the run- 3, of; Whichwhen the dipoles are differentially connected,

nection with the loop I.

ways by a reversible motor 20 by means of a screw 2| threaded through nut portions 22 in the carriage and geared, as at 23, to high ratio reduction gearing 24 carried by the motor.

The carriage I9 mounts a pair of rails or the like 25, at right :angles to the rails I1, and a carriage 26' has rollers 21 which ride on the rails 25. A reversible motor 28 is connected through high ratio reduction gearing 29 to a screw 30 threaded in a nut ear 3I on the carriage 26, so that operation of this motor will drive the carriage 26' to an adjusted position crosswise of the direction through which carriage I9 may be moved by motor 20.

A receiving antenna base 32 is trunnioned for tilting movement on the carriage 26, as by some such means as those shown at 33, 34. The means 34 may be a shaft driven by the reversible motor 35 having?highratiozreduction gearing 3B.

The antenna base :32 carries a step bearing 31. for the stem of the. loop I. is a bevel gear or the'like 38, meshed with the driving pinion of a reversible motor having reduction gearing like those of the other motors.

The motor 3.9 functions to. rotate the loop to any adjustedposition.

All the working parts between the loop 'I and the pedestal 9 are preferably protected by a.wa-.

terproof housing. or shield 40, which conveniently extends to a bottom plane somewhat lower than that showninFigJS.

It will be understood that appropriate circuits and control switches are provided for the several' motors so that they may be energized, under the control of an operator in the instrument room of the station, to'move the antenna I accurately to any adjusted position within its range of movement to make this antenna responsive to signals from the main station and substantially mire-- sponsive to the signal re-radiated by antenna 3 In substitution for the loop I we may use any other convenient type of repeater station receiv-- ing antenna. In Figs. 7 and 8 we show such a substitute antenna. It consists of two horizontal dipolesdl, 4|, placed in the same plane and at right angles to each other and mounted so that the vertical plane. of one of .them includes the main station. The dipoles are differentially connected to the transmission line 2 or to a preamplifier, as in the case of the loop I. The responses of the two similar dipoles to impulses from the vertical radiator 3 are similar, and,

these responses produce zero or substantially zero response in the following circuit. The responses of the two dipoles tosignals from the mainsta tion, however, are not similar and do not cancel to a small value when differentiallyconnected.

The electrical connections of the dipole an tenna are shown in Fig. -7, and it will be understood that the dipole antenna is mounted and adjusted precisely as has been explained in-con- Fig. 9 illustrates a modification of the embodi- Fast on this stem.

anced out but are made additive.

aesaiec ment of the invention-which'is shown in Fig. 5. As has been seen, those portions of the loop or other form of satellite receiving antenna which are of necessity responsive to the signal from the satellite radiator may be differentially coupled'to cause the response in such portions to balance to zero or some substantially low value. This fact permits the use of receiving antenna portions physically detached and separated from each other, provided they be difierentially connected electrically. The receiving antenna may therefore assume the form of separate loops or the like, as shown in Fig- 9. In this figure each of the two loops 42 is positioned in a field of more than minimum response to signals from the radiator 2, but the signal is balanced out or balanced to some low value. The orientation of the loops or the like 42 is such that their several responses to the signal from themain station are not bal- Adjusting means like that hereinbefore described may be provided for each of the two loops or the like 42, or iorone of them merely. In the latter case the other loop will be fixed approximately or roughly in position, and the adjustable loop will be moved to effect the desired balancing, so that the relative positions of the two loops will be correct and can be adjusted from time to time as occasion may require to maintain the necessary balance.

' It will be understood that the specific adjusting means hereinabove disclosed is given merely by way of exemplifying a practical embodiment of the invention. The specific features of this arrangement form no part of the invention broadly considered, since other means may be readily substituted therefor. Similarly, the sending antenna of the rep-eater station need not be shuntfed, as in the apparatus selected to illustrate a practical embodiment of the invention. The invention may be practiced with the insulated type of vertical radiator, and other changes, substitutions and omissions may be practiced without departing from the essential principles of the invention pointed out by the appended claims.

We claim:

1. An antenna system for a satellite station of the type in which the received and re-radiated Waves are of the same frequency, said system comprising a sending antenna having adjacent thereto a field of minimum intensity, a receiving antenna for said station, and means adjustably mounting said receiving antenna in said field comprising a member supporting the receiving antenna, a second member mounting the first member for rectilinear movement thereon, a support for the second member, and means moving the second member on said support rectilinearly to the direction of the first named movement.

2. An antenna system for a satellite station of the type in which the received and re-radiated waves are of the same frequency, said system comprising a sending antenna having adjacent thereto a field of minimum intensity, a receiving antenna for said station, and means adjustably mounting said receiving antenna in said field comprising a member supporting the receiving antenna, a second member mounting the first member for rectilinear movement thereon, a support for the second member, means moving the second member on said support rectilinearly to the direction of the first named movement, and

of the type in which the received and re-radiated waves are of the same frequency, said system comprising a sending antenna having adjacent to it a field of minimum intensity, in combination. with a receiving antenna comprising-loops each positioned-on an opposite side of; said :field and oriented so as to be; responsiveto a main station and differentially connected to balance responses to the sending antenna of the satellite station, and means for reducing to a minimum the response of the receiving antenna tmthe' sending antenna comprising means forjmoying at least one of said loops relatively to the sending antenna. f I I 4. An antenna system for a satellite station of the type in which the received and re-radiated waves are of the same frequency,.said system comprising a sending antenna in the form of a tower having above its upper end and in the line of its axis a field of minimum intensityand' a receiving antenna supported on the towergand projecting above the same and having its; parts substantially symmetrically disposed in said field.

5. An antenna system for a satellite station of the type in which the received and re-radiated waves are of the same frequency, said system comprising a sending antenna in the form of a tower having above its upper end and in the line of its axis a field of minimum intensity and a receiving antenna comprising a loop supported on the tower and projecting above the same and having its parts substantially symmetrically disposed in said field.

6. An antenna system for a satellite station of the type in which the received and re-radiated waves are of the same frequency, said system comprising a sending antenna in the form of a tower having above its upper end and in the line of its axis a field of minimum intensity and a loop receiving antenna comprising portions supported on the tower and projecting above the top thereof and substantially symmetrically disposed with a relation to said line.

7. An antenna system for a satellite station of the type in which the received and re-radiated waves are of the same frequency, said system comprising a vertical sending antenna portion having above its upper end and in the line of its axis a field of minimum intensity, in combination with a loop receiving antenna having parts positioned in said field on opposite sides of said line and substantially symmetrically disposed with relation to said line.

8. An antenna system for a satellite station of the type in which the received and re-radiated waves are of the same frequency, said system comprising a vertical sending antenna portion having above its upper end and in the line of its axis a field of minimum intensity, in combination with a loop receiving antenna positioned above the vertical antenna portion and in said field, all parts of the loop receiving antenna being substantially symmetrically disposed with relation to said line.

9. An antenna system for a satellite station of the type in which the received and re-radiated Waves are of the same frequency, said system comprising a vertical sending antenna having above its upper end a field of minimum intensity, in combination with a receiving antenna mounted in a zone including said field, and means for reducing to a minimum the response of the receiving antenna to the sending antenna comprising means for moving one antenna with relation to the other.

10. An antenna system for a satellite station of the type in which the received and re-radiated waves are of the same frequency, said system comprising a fixed vertical sending antenna having above its upper end a field of minimum intensity, in combination with a receiving antenna mounted in a zone including saidfield, and means for reducing to a minimum the response of the receiving antenna to the sending antenna comprising means for moving the receiving antenna.

11. An antenna system for a satellite station of the type in which the received and re-radiated waves are of the same frequency, said system comprising a vertical sending antenna having above its upper end and in the line of its axis a field of minimum intensity, in combination With a receiving antenna having a substantially vertical axis positioned in said field so as to be approximately coincident with said line, and means for reducing to a minimum the response of the receiving antenna to the sending antenna comprising an adjustable device having relatively movable elements connected to the receiving antenna and to the sending antenna respectively for changing the relative positions of said antennas whereby said axis of the receiving antenna may be maintained accurately coincident with said line.

12. An antenna system for a satellite station of the type in which the received and re-radiated waves are of the same frequency, said system comprising a vertical sending antenna having above its upper end and in the line of its axis a field of minimum intensity, in combination With a receiving antenna mounted approximately in said field and having a vertical plane substantially containing said line, and means for reducing to a minimum the response of the receiving antenna to the sending antenna comprising mechanism operable for substantially universal movement of the receiving antenna for moving the receiving antenna so as to maintain said plane in a position including said line and the parts of the receiving antenna symmetrical with said line.

JAMES C. MCNARY. JOSEPH A. CHAIVLBERS. 

